Experimental Study On Processes Of Metal Slurry's Non-pressing Casting And Sintering Based On Rapid Prototyping

Currently, more and more methods of rapid tooling based on rapid prototyping & manufacturing (RP&M) are developed. According to the different kinds of the mould materials, they are basically divided into the simple soft mould and steel hard mould. The characteristics of rapid steel hard mould can help designers to effectively and quickly convert their concepts to trial products. Once the trials are successfully conducted, people can use steel hard mould to produce applied products. Meanwhile companies need to explore and train the markets for their new products to gain the majority market shares and build the advantages over their competitors. Therefore, a big amount of effort has been donated to the research and development of rapid steel hard mould both domestically and internationally.After conducted a comprehensive analysis of different methods of rapid tooling based on RP&M, experimental study on processes of metal slurry's non-pressing casting and sintering based on RP is put forward. This technique is a combination of RP&M and powder metallurgy, and it creates a new way for rapid steel hard mould.Metal's slurry is a kind of liquid slurry material which is a mixture of certain proportion of organic liquid viscidity material and metal powder, while the viscidity material should choose liquid epoxy resin which has better fluidity. The imported DPI-400 caloric solid resin, local 196# non-saturation polyester resin and local 199 non-saturation polyester epoxy resin are respectively chosen as viscidity material. The experiment results show that the local 199 non-saturation polyester epoxy resin is the most suitable viscidity material for this experiment.To deeply explore the metal powder utilization, mathematical models have been studied regarding to two types of iron powder with different grain diameters. And their order quality match formula is educed based on the model. In the experiment, the mixing machine fully mixes the two types of iron powder mixture to make the even density. Then using this double modality iron powder mixture and simple fine carbonyl iron grains to make up four identical trial groups and comparethose groups. The results show that the adoption of two double modality iron powder mixture has two apparent advantages: from microcosmic perspective, the dense iron grain structure makes the sintering sample solider, thereafter the cubage content of viscidity material is reduced and it is good for viscidity material to be burnt off; at the same time, the carbonyl iron grains can fill up the gaps among the iron powder grains with larger diameter which helps to prevent viscidity to accumulate into conglobation. As a result, the viscidity can be evenly distributed among iron powder grains. Meanwhile a better structure can be built up between small and large grains which provide free channels for viscidity material to be burnt off.Metal slurry's non-pressing casting and sintering technique do not need pressure, but gravity to directly cast the metal slurry into the soft silicon rubber mould made in advance. The article did deeply research on some key techniques in terms of the material selection, slurry fluidity control and metal slurry's casting etc.Some samples got by metal slurry's non-pressing casting are sintered with hydrogen's protect. Some reasonable sintering criterions have been withdrawn from the experiments as follows: at the beginning of the sintering period, give longer and continuously low temperature sintering and the viscidity material of the trial products will be evenly burnt off. Whereafter, the temperature is increased gradually until it is just below 900°C which is the margin temperature of iron liquid melt, to sinter the iron grains to accumulate together which helps to achieve metal-skeleton structure products.Finally, the article introduces the results of the metal slurry's non-pressing casting and sintering technique to practical application. The practical application proves that metal slurry's non-pressing casting and sintering technique can make good final metal-skeleton structure products, and also the results show that the research provides essential fundamental theories and technique supports for rapid steel hard mould.